The invention is directed to a process for obtaining phenylalanine-dehydrogenase containing microorganisms, microorganisms which contain phenylalanine-dehydrogenase and their use for the production of L-.alpha.-aminocarboxylic acids.
The use of enzymes as catalysts has proven advantages in the sterospecific production of L-phenylalanine. It is known from German OS 3307095 to reductively aminate phenyl pyruvate with a phenylalanine-dehydrogenase and to obtain the corresponding enzyme from Brevibacterium spec. (DSM 2448). However, the thus isolated enzyme has been found to be relatively unstable.
Attempts to obtain additional microorganisms which contain phenylalanine-dehydrogenase with the help of the methods described there have not led to success.
This is founded on the fact that the nutrient medium known from German OS 3307095 makes possible an unspecific growth of different microorganisms, which naturally makes very difficult the selection of the desired strains.
The problem of the present invention was to develop a process for the isolation of phenylalanine-dehydrogenase containing microorganisms which make possible a quick selection of suitable strains and a stable phenylalanine-dehydrogenase.